1. I think it would be nice to have a unified system of checking for new plugins and installing any new desired plugins from inside C2. Correct me if I am wrong but I think the way it currently works is by posting new plugins in the forums (such as scirra.com/forum/zack0wack0s-construct-2-plugins_topic43422_post271418.html where you download them and manually install them. I am thinking about a system that would allow you to check for and install new plugins from inside C2 (and then perhaps restart C2 (if needed) after new plugins are installed). It would also be nice to have which versions of C2 (r51 for example) the plugin has been successfully tested in. Also giving it the ability to detect, download and install an updated version of a previously installed plugin would also be great. This would also probably include some extra work on the web site.
Yes, basically every game engine has their own little asset library like this. If you allowed people to upload content too, like images and audio, it would be nice. Not necessary to have the files stored on the site too, you could make it download from a remote repository which would have an update notice file with the latest version information.
Also, yes I really do want to work on the physics plugin! I'm just finding it hard to get motivated to make it because hilariously enough I hate event driven game engines.
EDIT: I'll try and work on it this weekend. I think I already said that, but this is the first free weekend coming up I've had for a while.